Alumino-thermic steel



Patented July 21, 1931 1,815,052

UNITED STATES PATENT {OF E JOHN H. DEPPELER, OI WEEHAWKEN, NEW JERSEY ALUMINO-THERMIC STEELv No Drawing. Application filed April 17, 1929. Serial No. 355,982.

The invention relates to an improved for practical welding purposes, in thatit. thermit steel involving high ultimate lacked the requisite tensile strength, although strength without the usual decrease in ducit possessed a high degree of ductility. Suctility, the im roved qualities of the steel beceeding developments introduced a percenting due to the presence therein of mangaage of mild steel punchings and gradual in- 5 nese, carbon and aluminum within prescribed creasing quantities of manganese and carlimits. bon, until there was produced a, material Alumino-thermic welding has been pracknown in the trade as railroad thermit, ticed for almost thirty years and the v process which is a steel containing approximately has developed gradually from a very crude 10% to carbon and .4070 manganese, 10 beginning, as the result of continued re- Further increases were made occasionally in search, until the inherent defects in the the carbon content where greater strength welds, such as blow-holes, cleavage planes, or hardness was required, but any increase and shrinkage cavities, which tended to proin the manganese content above 40% ap- 16 duce inherent weaknesses in the thermit parently greatly impaired the physical welds, have been eliminated and more attenproperties of the steel and rendered it untion has been given to improvement of the suitable for welding purposes. It was physical qualities of alumino-thermic steel. known, of course, that manganese produced Steel made by the reduction of metallic this undesirable efi'ectin the ordinary steels,

2 oxides by means of aluminum has in general but usually this was not important until the; 20 very different properties from ordinary steel contained more than 1% of manganese, steels. In the first place, ordinary steels are but, in thermit steels, there is left lnvarithe result of a refinement of metal reduced ably a fractional percentage of aluminum from impure iron ore and its refinement is in the steel, which apparently materially 35 carried on, not to completion, but to a point changed the physical effects of manganese. where commercially good results are obon the steel as compared to similar effects of tained and, as a consequence, when these like quantities of manganese employed in commercial steels are employed in casting ordinary steels.v operations, there are numerous impurities In developing the present invention, I

80 therein, which, as the metal cools, are thrown made careful tests with increasing quantiout to the grain boundary and introduce an ties of manganese, both with and without element of Weakness there. Aluminoincreasing percentages of carbon in the thermic steels, on the other hand, are made alumino-thermic steel, but always with a by the reduction of exceptionally pure metalrelatively small percentage of aluminum,

lic oxides by means of'pure aluminum, with varying from .01% to-1%, and discovered 35 the result that these steels are purer than that with increasing quantities of mangaeven ultra refined steels made by the usual nese, the measurements of tensile strength method. Cast steels made by the aluminoand elongation showed that these thermit thermic process have, therefore, no such steels passed through a critical stage in 40 weaknesses at the grain boundaries and exwhich the manganese content varied from 4 hibit all of the physical properties of forged 40% to .50% and, in some cases, as high as steels of the prior art, except that of appear- .60%, and that immediately after this critiance under a microscope. cal range, that is to say, with higher per- The original thermit steel was, as a consecentages of manganese, for example .65%

quence of the method, a low carbon material to .70%, the physical properties were great- 4 roduced by the reduction of pure iron oxide 1y improved, the ultimate strength increas- Ey means of aluminum, and this material was ing to as high a figure, for example, as 7 5,000 in effect a soft iron with carbon below 10% lbs. per square inch, without a corres 0nd and practically no other impurity. It was ing decrease in ductility, which had a ways 9 soon found that this was too soft a material been experienced where the ultimate strength had been increased by carbon additions alone. Ultimately there was develed a steel possessing the desired ualities 0 high ultimate strength and ductility 5 aforesaid that was particularly well adapted for use in therm1t welding and that produced better results than any hitherto known steel, the critical limits being between 55% and .80% manganese, between 20% and 1 .40% carbon, and between .01% and 1% aluminum.

A typical alumino-thermic mixture that, upon reaction, will produce the new steel containing approximately Mn .67 and G 30% is as follows, the proportions indicated being by weight:

Per cent Pulverized aluminum "20.8 Roasted mill scale "64.7

Manganese ore (MnO 1.0 Mild steel punchings 12.8 Pulverized hard coal .7

What I claim is: 1. Alumino-thermic steel containing from 55% to .80% manganese, from 20% to 40% carbon, and from .01% to 1% aluminum.

2. Alumino-thermic steel containing approximately .65% manganese, approximately 25% carbon and not less than .01% or so more than 1% aluminum.

In testimony whereof I aflix my signature.

JOHN H. DEIPELER. 

